The present invention relates to a switch device, particularly for use in automotive vehicles, in which the current through a load can be switched as a function of a physical variable acting on the switch device.
Switch devices in which a load is switched on or off as a function of a physical variable acting on a switch device are frequently used in automotive vehicles. The switch devices can be developed for instance as pressure, temperature, level or distance switches, and generally serve for the switching of warning lights, buzzers or relays. Due to advances in the field of semiconductors, the traditional switching devices of mechanical construction are being replaced to an increasing extent by electronic sensors which give off a switch signal when the physical variable exceeds or drops below a predetermined threshold value. By the use of electronic components there are obtained, inter alia, advantages in manufacture, a reduction in size, a shortening of the response time, and in many cases even a lower price.
One essential disadvantage of such known electronic 2-point sensors is, however, that three connections are necessary, namely one for ground, one for the operating voltage, and one as switch output. In this way there is an additional expense for connectors and lines as compared with the traditional mechanical 2-point sensors.